Semipalatinsk Test Site
Operation First Lightning, the first Soviet atomic test
Type	Nuclear test site
Location	_ 5007′N, 7843′E|] near Kurchatov in Kazakhstan
Area	~6,950 mi² (~18,000 km²)
Operator	Soviet Union
Status	Inactive
In use	1949 – 1991
Testing
Subcritical tests	not known
Nuclear tests	456
The 18,000 km 2 expanse of the Semipalatinsk Test Site (indicated in red), attached to Kurchatov (along the Irtysh river), and near Semey, as well as Qaraghandy, and Astana. The site comprised an area the size of Wales

The Semipalatinsk Test Site (STS) was the primary testing venue for the Soviet Union's nuclear weapons. It is located on the steppe in northeast Kazakhstan (then the Kazakh SSR), south of the valley of the Irtysh River. The scientific buildings for the test site were located around 150 km west of the town of Semipalatinsk (later renamed Semey), near the border of East Kazakhstan Province and Pavlodar Province with most of the nuclear tests taking place at various sites further to the west and south, some as far as into Qaraghandy Province.

The site is also known variously by its postcode Semipalatinsk-21 (it was common practice for secret Soviet installations to be referred to only by their nondescript postcode), the Semipalatinsk Polygon, and latterly the National Nuclear Center of Kazakhstan.

The site was selected in 1947 by Lavrentii Beria, political head of the Soviet atomic bomb project (Beria falsely claimed the vast 18,000 km² steppe was "uninhabited"). Gulag labour was employed to build the primitive test facilities, including the laboratory complex in the northeast corner on the southern bank of the Irtysh River. The first Soviet bomb, Operation First Lightning (nicknamed Joe One by the Americans) was conducted in 1949 from a tower at the Semipalatinsk Test Site, scattering fallout on nearby villages of Kazakh nomads (which Beria had neglected to evacuate). The same area ("the experimental field", a region forty miles west of Kurchatov city) was used for more than 100 subsequent above-ground weapons tests.

Later tests were moved to the Chagan River complex and nearby Balapan in the east of the STS (including the site of the Chagan test, which formed Lake Chagan). Once atmospheric tests were banned, testing was transferred to underground locations at Chagan, Murzhik (in the west), and at the Degelen Mountain complex in the south, which is riddled with boreholes and drifts for both subcritical and supercritical tests. After the closure of the Semipalatinsk labour camp, construction duties were performed by the 217th separate engineering and mining battalion (who later built the Baikonur Cosmodrome). Between 1949 and the cessation of atomic testing in 1989, 456 explosions were conducted at the STS, including 340 underground (borehole and tunnel) shots and 116 atmospheric (either air-drop or tower shots). The lab complex, still the administrative and scientific centre of the STS, was renamed Kurchatov City after Igor Kurchatov, leader of the initial Soviet nuclear programme. The location of Kurchatov city has been typically shown on various maps as "Konechnaya" (the name of the train station; now Degelen) or "Moldary" (the name of the village that was later incorporated into the city).

The site was officially closed on August 29, 1991.

The Semipalatinsk complex was of acute interest to foreign governments during its operation, particularly during the phase when explosions were carried out above ground at the experimental field. Several U2 overflights examined preparations and weapons effects, before being replaced with satellite reconnaissance. The US Defense Intelligence Agency is said to have been convinced that the Soviets had constructed an enormous beam weapon station at the STS (which wasn't the case). Some reports even claim the CIA experimented with remote viewing, hoping to glean details of activities at the STS by psychic means.

Semipalatinsk also hosts three of Kazakhstan's four nuclear reactors. The IGR complex hosts one 50 megawatt graphite‐moderated reactor. The Baykal-1 complex hosts two: a 60 megawatt water‐moderated reactor and a small uranium zirconium hydride research reactor (which is now disused). The laboratory complexes also contain two cyclotron laboratories and two particle accelerators.

Semipalatinsk was the site that Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan chose for the signing of the Central Asian Nuclear Weapon Free Zone on September 8, 2006, also commemorating the 15th anniversary of the test site's closing.

See also

• List of nuclear reactors
• Novaya Zemlya Test Site

External links

• Semipalatinsk test site's website
• Semipalatinsk test site's panoramic photos
• The Nuclear Threat Initiative's page on the STS
• Environmental study of the site's atomic legacy (PDF file)
• detailed seismic data for world nuclear tests - shows all explosions at STS from 1966 (PDF file)
• nuclearweaponarchive.org/ on the Soviet nuclear program
• Details of nuclear explosions at STS, including detailed map of fallout trails
• City of Kurchatov (from the site of the East Kazakhstan provincial government) (in Kazakh)

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